Composite metal/concrete floor and method

ABSTRACT

A composite metal/concrete floor system and method of installation. The system includes a novel decking profile; snap-in cover plates to provide longitudinal cells for three services; a lateral trench with sheet metal rails and bottom plates; and cooperating present inserts. The deck and cover plate may be used as distribution cells suspended between the bar joists of a formed deck.

BACKGROUND OF THE INVENTION

The present invention relates to an improved electrified compositemetal/concrete floor.

Such floors are well known and comprise a corrugated metal decking overwhich concrete is poured. Such floors are often electrified in thatelectrical power and telephone and other communication services aredistributed in the cells underlying the raised portions or crests of thedecking, with access to the interior of the cells from the upper surfaceof the floor provided by inserts preset at selected intervals prior tothe concrete pour. Access by the services to the interior of thelongitudinal cells is generally provided by a lateral trench overlyingthe metal decking, which trench includes parallel rails covered with ametal plate coplanar with the upper surface of the concrete floor whenpoured.

In one aspect, the present invention includes a novel metal deckingprofile, with grooves adjacent the lateral edges of the crests toreceive the concrete of the composite floor, stable when stacked duringshipment to the job site.

Grooves adjacent the crests of decking to receive concrete are wellknown. For example, FIG. 4 of the French Patent No. 1,176,824 grantedNov. 28, 1958 to Wendel shows a decking profile in which the radii ofthe bend at the lateral edge of the crest and the bottom of the grooveare equal and in which the centers for the bends are vertically spacedapproximately twice such radii. Concrete enters the groove to enhancethe metal/concrete interaction, i.e., "composite action", when theconcrete is poured. Stacking is stabilized by making the radius bend ofthe lateral edge of the lower side of the groove slightly larger thansuch radii to mate with the lateral edge of an underlying deckingmember. However, the semi-cylindrical radius bends do not provideadequate deformation resistance to downward pressure from the lateraledges of the crests.

Grooves adjacent the lateral edge of metal decking are also shown in theTing U.S. Pat. No. 4,453,364 dated June 12, 1984. In that patent, thegrooves have a horizontal lower side and an upper side joining theradius bend of the lateral edge of the crest at an angle ofapproximately forty-five degrees. The Ting grooves are constructed suchthat (a) the lateral edge of the crest is at or inside of the plane ofthe sidewall and (b) a vertical line passing through the lateral edge ofthe crest intersects the sidewall structure at a point inside the planeof the sidewall, i.e., intersects a groove in the sidewall rather thanthe sidewall or any projection therefrom. While bending resistance isenhanced, the amount of concrete which can enter the groove isinadequate when cover plates are used. Moreover, the location of thelateral edge of the crests interiorly of the intersection of the planesof the sidewall and the crests results in instability in stacking.

The decking profiles of the present invention combine the stackingstability and metal/concrete interaction of Wendel with the improvedstrength of Ting, and further enhance the metal/concrete interaction. Inone embodiment, this improvement is obtained by increasing the verticalseparation of the centers of the radius bends of the crest and groove soas to join the groove and crest edge at an angle of approximatelyforty-five degrees. Stacking stability is enhanced by the matching ofthe radius bends of the side wall and crest. In another embodiment, thedecking profile of the present invention further enhances compositeaction by establishing a projection in the side wall immediately belowthe groove to thereby extend the horizontal lower wall of the groove.Stability when stacked is enhanced by the abutment of the projectionwith the side wall at a point on the side wall below the crest.

In other embodiments, the center of the projection is displacedoutwardly so as to increase the shoulder on which cover plates may rest.

In another aspect, the decking profile of the present invention has acentral valley significantly wider than the side-lap valleys and widerthan the crests. Conventional decking sections such as disclosed in theAlbrecht, et al. U.S. Pat. No. 3,812,636 dated May 28, 1974, and theaforesaid Ting patent have central and side lap valleys of approximatelyequal width.

A third embodiment of the decking profile of the present inventionprovides adequate space for the use of studs in securing the side-lapvalleys to the structural beams, while greatly increasing the effectivespace in the central valley where the services are provided. Thestructural properties of the sections are enhanced by upwardlyprojecting cell dividers as explained infra in more detail.

In a fourth embodiment, the cell dividers in the central valley deckingprofile are elevated to a height adjacent the height of the crests,further enhancing the structural properties of the decking member andpermitting the use of lighter gauge metal. Raising the cell dividersalso increases the capacity of the central cell.

The elevation of the cell dividers permits attachment of the presetinserts through the cover plate directly to the decking member, therebyproviding an electrical ground and avoiding the necessity for a securemetal-to-metal attachment of the cover plate to the decking member alongthe lateral edges of the cover plate. The elevation of the cell dividersalso permits the use of the same cover plate with decks of differentdepth.

In another aspect, the present invention includes snap-in cover platesfor selected valleys of the decking to form longitudinal cells forelectrification of the floor. Longitudinal cells for this purpose arewell known. They may be formed by welding of the decking to anunderlying plate as disclosed in the Penczak U.S. Pat. No. 4,041,238dated Aug. 9, 1977, the Fork U.S. Pat. No. 4,178,469 dated Dec. 11,1979, or No. 3,426,802 dated Feb. 11, 1969; or the Littrell U.S. Pat.No. 4,338,484 dated July 6, 1982. They may also be formed by snap-inplates beneath the crests of the decking as disclosed in the Fork U.S.Pat. No. 4,194,332 dated Mar. 25, 1980, and the Albrecht, et al. U.S.Pat. No. 3,812,636 dated May 28, 1974. The decking, however, isstructurally weakened by the apertures necessary for access to thecells.

Others have avoided the problem of decking penetration by providingcover plates for a valley to thereby create a longitudinal cell withinthe valley. Systems of this type are disclosed in the Fork European Pat.No. 0003506, the Fork U.S. Pat. No. 3,592,956 dated July 13, 1971, orthe Lee, et al. U.S. Pat. No. 2,912,848 dated Nov. 17, 1959.

However, such systems generally provide a smooth upper surface withreduced composite action, do not provide for separation of serviceswithin the cell, span the valley without intermediate support, are notresiliently compressible for snap-in and do not have upturned lateraledges for prevention of water seepage during the concrete pour.

Other systems, such as disclosed in the Ting U.S. patent applicationSer. No. 340,869 filed Jan. 20, 1982 (now abandoned), utilize groovesadjacent the crests for retention of the flat cover plates. Whilelowering the cover plate provides an upturned edge for prevention ofwater seepage, the reduced height of the cell is generally unacceptablebecause of the resultant reduced capacity for all services, and thecapacity (i.e., crosssectional area) determines the number of wires andhence the length that a cell can branch out from the feeder or trenchheader. The aforementioned Ting application also teaches support of thecover plates intermediate the crests by two interconnected but spacedapart legs which separate the valley into two equal volume cells.However, such cover plates rely on concrete between the legs forstrength, and thus further reduce the volume or capacity of the twocells, i.e., the use of parallel legs spaced sufficiently apart forconcrete to enter therebetween significantly reduces the capacity of thetwo cells.

The cover plates of the present invention are stackable for shipment tothe job site and are easily installed from above the decking. Ascontrasted with decking which must span from beam to beam and is thusinstalled by steel workers, the cover plates may be of shorter lengthand installed by electricians walking on the deck, thus greatly reducinginstallation costs.

The cover plates may provide two unequal capacity cells, or three cellsof the same or different capacity, in the same valley. In oneembodiment, they may be made of sheet metal and provided with one or twodouble walled legs to provide support intermediate the crests. The legsmay be shaped and/or otherwise constructed to enhance lateral resiliencyand thus secure a positive snap-lock engagement with the grooves.Metal/concrete interaction is retained and additional space for threeservices is provided by the selective raising of a portion of the coverplate above the point of connection thereof to the sidewalls, even tothe same height as the crests, and by the substantial elimination ofconcrete between the walls of the legs. The decking profile permits theentry of significant concrete into the grooves with the lateral edges ofthe cover plate engaged therein, and even with the lateral edges of thepreset inserts engaged therein as described infra. In three cellembodiments, the center section may be lowered to facilitate access tothe two side cells. This lowering of the center cell provides adequatespace for the nearly vertical mounting of electrical receptacles andincreases the volume and thus the capacity of the preset inserts tohouse related accessories.

In still another aspect, the present invention includes a preset insertuniquely cooperating with the cover plates for access to the cellsdefined by the valley of the decking member and the cover plate. Knownpreset inserts such as disclosed in the Fork U.S. Pat. No. 3,932,696dated Jan. 13, 1976 and Penczak U.S. Pat. No. 4,041,238 dated Aug. 9,1977 span adjacent crests and are designed to provide access to cellsbeneath the crests. Others, such as Fork U.S. Pat. No. 3,417,191 datedDec. 12, 1968, fit between the crests to provide access to cells beneaththe crests, and still others, such as Fork U.S. Pat. No. 3,592,956 datedJuly 13, 1971, span two crests to provide access to cells beneathadjacent crests as well as a cell in the intervening valley. All requirepenetration of the decking.

In various embodiments, the preset inserts of the present invention arenestable to facilitate safe shipment to the job site, may be constructedof sheet metal, provide ready access to all three longitudinal cells,and cooperate with snap-in electrical power receptacles.

In the present invention, preset inserts may be carried solely by thecover plates, or by the decking, or by both. They may cooperate insnap-lock fashion with the grooves in the sidewal of the decking alongthe cover plate without significant diminution of the capacity of thecell, or may be snapped into apertures in the cover plate. In oneembodiment, they may be secured directly to the cover plate and/or thecover plate and decking by threaded fasteners without penetration ofsuch fasteners into the cells.

In yet another aspect, the present invention includes a novel lateraltrench for distribution of the services to the longitudinal cells. Priorart trenches, such as disclosed in the Fork U.S. Pat. No. 3,886,702dated June 3, 1975, generally extrude vertically adjustable side railsof aluminum. Many of the above, such as Fork, et al. U.S. Pat. 3,932,696dated Jan. 13, 1976 and Penczak U.S. Pat. No. 4,056,896 dated Jan. 3,1978, utilize the decking as the floor of the trench. Such trenches areoften referred to as "bottomless". However, the use of the valley flooras the bottom of the trench requires that the concrete be interrupted bydepending dams or stops in the valleys beneath the rails to preventfilling of the trench with concrete flowing upwardly from the valleysunderlying the trench. The use of vertical concrete stops which dependinto the intervening valleys interrupts the concrete beneath the trenchand thus effects a significant loss of strength of the completed floor.

The present invention in various embodiments provides rails of sheetmetal of greatly reduced cost, and snap-in bottoms for the trenchintermediate the electrified cells. Such bottoms may be supported by thecrests, spanning at least two of them and the included valley, andengaging the grooves in the sidewall on the outside of the deckingsections. Concrete may thus flow uninterrupted through thenon-electrified valley beneath the trench, significntly enhancing thestrength of the composite deck.

In other embodiments, the trench bottom plates have upturned lateraledges to position the trench side rails and a pair of spaced ridges toposition the power channel within the trench.

In a further aspect, the decking members, cover plates and presetinserts of the present invention may be used to electrify a formed decksupported by bar joists. Such decks are generally electrified by thesuspension of a header duct between selected pairs of bar joists and bydistribution ducts overlying the corrugated deck which serves as theform for the concrete slab. Ducts of this type are generally factorywelded and non-nestable. More importantly the capacity of thedistribution duct and the preset inserts is limited by the depth of theconcrete slab. The present invention permits reversal of the position ofheader and distribution ducts and thus provides significantly increasedcapacity for the electrical services with a reduced slab thickness.

These and the many other aspects and advantages of the present inventionmay more readily be understood from the claims and from the followingdetailed description when read in conjunction with the appendeddrawings.

THE DRAWINGS

FIG. 1 is an end view in elevation of one embodiment of a decking memberof the present invention;

FIG. 2 is a section in elevation of the decking member of FIG. 1 withconcrete poured thereon illustrating the concrete decking memberinterface;

FIG. 3 is a partial section in elevation taken through lines 3--3 ofFIG. 2;

FIG. 4 :s a pictorial view, partly exploded, illustrating the assemblyof one embodiment of the electrical distribution system.

FIG. 5 is a section in elevation illustrating one embodiment of thecover plate of the present invention in place over one of the valleys ofthe decking member of FIG. 1 to form a three electrical service cell;

FIG. 6 is a top plan view of the cover plate of FIG. 5;

FIG. 7 is a partial end view in elevation illustrating the attachment ofthe cover plate of FIGS. 5 and 6 to the decking member of FIG. 1, andillustrating the nestability of the decking members of FIG. 1;

FIG. 8 is a partial end view in elevation illustrating the attachment ofthe cover plate of FIGS. 5 and 6 to a second embodiment of the deckingmembers of the present invention, and illustrating the nestability ofthe decking members;

FIG. 9 is a pictorial view of one embodiment of the preset insert of thepresent invention;

FIG. 10 is a pictorial view in a partial section illustrating thecomposite floor of the present invention with a preset insert in placeover an electrified valley;

FIG. 11 is a top plan view of the preset insert of FIG. 9;

FIG. 12 is a section in elevation taken through lines 12--12 of FIG. 11;

FIG. 13 is an end view in elevation of the preset insert of FIG. 9;

FIG. 14 is a section in elevation taken through lines 14--14 of FIG. 11,illustrating the mounting of the electrical receptacles;

FIG. 15 is a pictorial representation of the electrical receptacle ofFIG. 14;

FIG. 16 is a top plan view of a second embodiment of the preset insertof the present invention;

FIG. 17 is a section in elevation illustrating the mounting of thepreset insert of FIG. 16 on an electrified valley;

FIG. 17A is a section in elevation illustrating any alternative insertlateral edge configuration;

FIG. 18.is a pictorial representation of the electrical receptacle ofFIG. 17;

FIG. 19 is a partial section in elevation illustrating the mounting ofthe electrical receptacle of FIG. 18 in the preset insert of FIG. 16;

FIG. 20 is a partial section in elevation taken through the center of anelectrified valley at the junction of the distribution trench andillustrating one embodiment of trench construction of the presentinvention;

FIG. 21 is a pictorial representation illustrating the configuration andmounting of the decking member end partition of FIG. 20;

FIG. 22 is a partial section in elevation taken through the center of anelectrified valley at the junction with the trench and illustrating asecond embodiment of the trench of the present invention;

FIG. 23 is a pictorial view of the decking member end partition of theembodiment of FIG. 22;

FIG. 24 is a pictorial view of a second embodiment of the trench bottomplates of FIG. 4 in which the bottom plate spans several valleys;

FIG. 25 is a partial section in elevation illustrating the endconstruction of the bottom plates of FIG. 24 and the mounting thereofwith the decking member of FIGS. 7 or 8;

FIG. 26 is a partial section in elevation illustrating the lateralconstruction and mounting of the bottom plates of FIG. 24 with thetrench illustrated in FIG. 20; and

FIG. 27 is a pictorial view of a third embodiment of the trench bottomplates of FIG. 4;

FIG. 28 is an exploded pictorial view showing the central cell partitionfor the trench and for an electrified valley in the area beneath thetrench;

FIG. 29 is a section taken through lines 29--29 of FIG. 28;

FIG. 30 is an end view in elevation of the decking section of FIG. 1 athird embodiment of the cover plate of the present invention in placethereon;

FIG. 31 is an end view in elevation of the decking section of FIG. 1with a fourth embodiment of the cover plate of the present invention inplace thereon;

FIG. 32 is an end view in elevation of a second embodiment of a deckingmember of the present invention with a fifth embodiment of a cover platein place thereon;

FIG. 33 is an exploded pictorial view of a second embodiment of thetrench of the present invention;

FIG. 34A is an elevation in cross-section of the portion of the deckingmember of FIG. 3 after the concrete pour intermediate the rails of thetrench with the power cell divider and trench bottom in place thereon;

FIG. 34B is an elevation in cross-section of the position of the deckingmember of FIG. 33 after the concrete pour outside the trench;

FIG. 35 is an elevation in cross-section of a third embodiment of atrench side rail;

FIG. 36 is a pictorial view of a fourth embodiment of the decking memberof the present invention with a cover plate in place thereon;

FIG. 37 is a pictorial view of a further embodiment of a preset insertconfigured for attachment to the decking member and cover plate of FIG.36;

FIG. 38 is a partial end view in elevation of a further embodiment ofthe decking member of the present invention;

FIG. 39 is a partial top plan view of a fifth embodiment of the coverplate of the present invention;

FIG. 40 is a section in elevation taken through lines 40--40 of FIG. 39;

FIG. 41 is a top plan view of a portion of the cover plate of FIG. 39with the knock-outs of the central cell removed;

FIG. 42 is a section in elevation taken through lines 42--42 of FIG. 41;

FIG. 43 is a section in elevation taken through lines 43--43 of FIG. 37showing the snap-in mounting of the electrical receptacles;

FIG. 44 is an exploded pictorial view of a further embodiment of thetrench bottom plate as power cell;

FIG. 45 is an elevation of a further embodiment of the trench rail withthe trench bottom plate of FIG. 44;

FIG. 46 is a top plan view of the decking system illustrating the use ofshort sections of cover plate to establish a pattern of offset rows ofpreset inserts;

FIG. 47 is a top plan view of the decking system illustrating the use ofshort sections of cover plate to establish a pattern of preset insertswith blended deck.

FIG. 48 is a pictorial view in partial section of a further embodimentof the present invention adapted for use with bar joist construction;and FIG. 49 is a schematic end view in elevation of the floor of FIG.48.

THE DETAILED DESCRIPTION The Decking Members

With reference now to the drawings, one embodiment of the decking memberof the present invention is illustrated in FIGS. 1-3. As shown therein,the decking member indicated generally by the numeral 30 includesalternating crests 32 and valleys 34. As shown in the system drawing ofFIG. 4, the decking members may each include two crests 32, a centralvalley 34A and with the lateral edges of the decking member 30 formingone-half of a side-lap valley 34B. The side-lap valley includes matingmeans such as an upturned edge 36 on one lateral edge and a downturnedgroove 38 on the other lateral edge. Of course, each decking member mayinclude additional crests and valleys. However, it is desirable to avoidpotential damage to electrical wiring from the rough lateral edges ofthe decking member and the crest-to-crest spacing of the side-lapvalleys is not adequately reproducible to insure proper operation of thesnap-lock of the cover plate therebetween. Therefore, only interior andcomplete valleys of a decking member will be electrified.

As shown in FIGS. 1-4, the crests 32 and valleys 34 are substantiallycoplanar and are interconnected by slanting sidewalls 33. The sidewalls33 may be provided with a series of embossments 40 extending into orprotruding from the sidewall to provide additional surface area andcorrugations for contact with the concrete thereafter poured thereon, asshown in FIGS. 2 and 3.

As shown in FIG. 1, each of the crests 32 may be provided with one ormore, preferably two, spaced stiffening beads 44 which enhance not onlythe structural strength of the crest but also the bonding of the deckingmember to the concrete when poured thereon.

As shown in FIG. 1, each of the valleys 34 may also be provided with twolongitudinal stiffening beads or projections 46 extending upwardly fromthe floor of the valley. In addition and to increase structural strengthfor the decking member 30, the projections 46 may include a groove 48 orother configuration for mating with the downward extending legs 64 ofthe cover plates of 50 shown in FIGS. 4-6 placed end to end over one ofthe valleys selected for electrification. The groove 48 providesincreased stability until the concrete has been poured, in that itresists rotation of the cover plates when subjected to the load ofconstruction traffic, etc. on the bends defining the lateral edges ofthe surface 56.

As shown in FIGS. 1, 2 and in the section of FIG. 5, the sidewall 33 ofthe decking member 30 includes an upper portion having a groove 52 and aprojection 54 immediately adjacent the groove 52. The sidewall 33 alsoincludes a substantially longer planar lower portion so that both thegroove and projection are in the upper portion of the sidewall adjacentthe crest.

While not shown to scale in FIG. 1, a typical decking member may beabout 3 inches deep, 30 inches wide and in 20 to 40 foot lengthsindependent of the length of the cover plates used thereon to create thelongitudinal cells. The width of the crests is generally less than thevalleys in a ratio of about 4:5. Moreover, the central valley may bewider than the side-lap valley by ten percent or more (about twenty-fivepercent as shown in FIG. 10) and desirably in a ratio of about 5:14 asshown in FIG. 32. This increased central valley width is significant inboth two and three cell embodiments, for it defines the total availablecapacity for the PLEC (power, lighting, electronic and communication)services contained therein.

With reference to FIG. 7 where the decking member of FIG. 1 isillustrated in greater detail, it may be seen that the groove 52 in theupper portion of the sidewall includes an upper leg 81 and a lower leg82. The upper leg is disposed at an angle A-3 of between about forty andabout fifty degrees to the horizontal and the lower leg 82 issubstantially horizontal and fairs smoothly into the horizontal portion84 of the projection 54. It may thus be seen that a vertical line 86dropped from the widest portion of the crests 32 intersects the uppersurface 84 of the projection 54 rather than the lower leg 82 of thegroove 52, i.e., it intersects the sidewall structure on or outside theplane of the sidewall 33. It may also be seen that the outermostprojection of the crest is laterally outside of the intersection 83 ofthe planes of the crest 32 and the sidewall 33, thus providing a greaterconcrete holddown.

With continued reference to FIG. 7, the projection 54 on the sidewall 33of the decking member provides increased stability for the lateral edgeof the cover plate where a groove 88 is rolled into the lateral edge ofthe cover plate 50. As illustrated in FIGS. 7 and 8, the radii of thegroove 88 and projection 54 may cooperate to increase stability. Thelocation of the aperture 74 in the bend disposes the aperture at anangle to the vertical which insures that a fastener placed therein willpenetrate the sidewall of the decking member and thus avoid the dangerof diversion into the electrified valley.

As may also be seen in FIG. 7, the decking member 30 of FIG. 1 may bestacked for shipment with the underside of the groove 52 supported bythe crest 32 of the underlying decking member. When so stacked, theprojection 54 engages the interior of the sidewall 33 of the overlyingdecking member to provide increased lateral stability to the stack ofdecking members.

In other embodiments, such as illustrated in FIG. 38, the center 300 forthe radius bend for the projection 302 may be outwardly displacedslightly from the centers 304, 306, for the radius bends of the crestand groove. In this way, the generally horizontal shoulder 308 may beenlarged for additional support of the cover plate without destroyingthe stacking stability thereof. Additional horizontal support for thestacking of the decking members may be provided by moving the center 306slightly inward of the center 304.

A second embodiment of the decking member of the present invention isillustrated in FIG. 8. With reference to FIG. 8, it may be seen that theprojection 54 of the embodiment of FIG. 7 may be omitted without losingthe desirable mounting relationship of the cover plate 50 therewith bythe lengthening of the upper leg of the groove 52. As shown in FIG. 8,the radius of curvature R-1 and R-2 are the same, with the radius ofcurvature R-3 being greater than R-1 by slightly more than the thicknessof the sidewall 33 of the decking member. In this way, the junction ofthe lower leg 82 of the groove 52 with the lower portion of the sidewallwill overlie the upper surface of the junction of the upper leg 81 ofthe groove with the crest 32 to provide lateral stability for thedecking members when stacked for shipment and for storage at the jobsite.

As may also be seen from FIG. 8, the latter edge of the crest is outsidethe intersection 83 of the planes of the sidewall 33 and crest 32 and avertical line 86 through the lateral edge of the crest will intersectthe sidewall structure at or outside the plane of the sidewall 33.

A third embodiment of the decking member of the present invention isillustrated in FIG. 32. As shown therein, the decking member maycomprise two crests 220 and a central valley 224 and the two halves 226of a side-lap valley. As illustrated, the width of the central valleymay be significantly increased over the width of the side-lap valley toprovide the room needed for three services, even in a relatively narrowdecking member. For example in a 24 inch wide decking member, the twocrests 220 may be approximately 2.5 inches in width, the two halves 226of side-lap valley approximately 2.0-2.5 inches each, and the centralvalley approximately 14 to 15 inches.

Each half of the side-lap valley provides adequate room for the weldingof a bolt 228 or other projection as a shear connector thereto and tosupporting beam 230. The concrete/steel interaction may thus beenhanced.

The increase in the width of the central valley requires the use of twostiffening ridges 232. These ridges 232 may approximate in height thegrooves in the sidewalls of the decking member and thus tend to raisethe neutral axis and thereby balance the decking member in compressionand tension.

As shown in FIG. 36, the height of the ribs 260 may be increased to anelevation intermediate the height of the crests 262 and the grooves 264,e.g., about 2.6 inches for a three-inch deck.

These ridges 232 also support the cover plate 234 and provide dividersfor the three services. Where the relationship between height of grooveon ribs is held constant for decking members of different depth, thesame cover plate may be used.

In addition, the top of the ridges provide a convenient location forattachment of preset inserts to the cover plate and to the deckingmember without risk of the fasteners protruding into the cells. Screwsmay be used in lieu of pop rivets and the necessity for the grounding ofthe cover plates to the decking member adjacent the grooves therein maybe obviated.

As shown in the embodiment of FIG. 36, the ridges 260 may extendupwardly at an angle of approximately 80 degrees to a height adjacentthe height of the crests 262, i.e., about 3/8 inch below the crests in a3 inch deck and thus about mid-height of the grooves 264. This additionof steel at this elevation, together with any increase in the width ofthe crests, raises the neutral axis of a three inch decking section fromabout 1.0 inch above the valley 266 to about 1.3 inches. The increasedstructural properties permits the use of a lesser gauge steel andsignificant cost savings.

A further increase in the structural properties of the decking memberresults from an increase in the width of the crests 262 and a furtherreduction in the width of the side-lap valleys 270 to about three inchesor about twenty-two percent of the width of the central valley 268 in a24-inch decking member. This narrowing of the side-lap valleys 270 toabout three inches for a two foot wide decking member results in acentral valley/side-lap valley width ratio of about 9:1.

If total electrification is desired, consecutive 30" wide members may beused to produce an electrified valley on 30" centers. To acheive thiswidth, the side-lap valley may be extended three inches on each side.This extension of the side-lap valleys also provides room for shearconnectors.

The decking members of the present invention may be blended withnon-electrified deck, using a two-foot decking member such asillustrated in FIG. 36 with one or two sections of nonelectrified deckto provide an electrified valley on four, five or six-foot centers, etc.

Because of the increased section properties of the electrified deck, alighter gauge metal may be used than is required for the conventionalnon-electrified decking.

The Cover Plates

The cover plate 50 of FIG. 4 is illustrated in greater detail in FIGS. 5and 6 and in a preferred embodiment includes three lateral sections,each of the two outer sections having a flat portion 56 at the sameelevation as that of the crest 32 and an outer edge portion at adistance D-1 below the elevation of the crest 32. As illustrated in FIG.5, the outer edge portion includes an edge upturned to present anoutwardly convex projection 58 for entry into the groove 52 formed inthe upper portion of the sidewall 33 of the decking member.

With continued reference to FIG. 5, the center section of the coverplate 50 includes a flat portion 60 interconnected with the flatportions 56 of the outer sections by the dual wall downwardly extendinglegs 62. The cover plate 50 is desirably onepiece construction with thedual wall leg 62 being open at the upper end and closed at the lower end64 to mate with the groove 48 in the upper surface of the projection 46.The height D-2 of the projection 46 above the valley is desirablydimensioned not only to provide stiffening of the valley floor of thedecking member, but to reduce the length of the leg 62 necessary tosupport the flat surfaces 56 of the cover plate substantially coplanarwith the crest 32.

As may be seen in FIG. 5, the lateral distance between the convexprojections 58 of the cover plate 50 is greater than the lateraldistance between the adjacent crest 32. However, the legs 62 act asspring members permitting resilient lateral compression of the upperportions of the leg 62 sufficient for the lateral edges 58 of the coverplate 50 to enter the grooves 52 beneath the crest 32. As shown in FIG.5, the dual wall leg 62 may be provided with a projection 66 or othermeans to enhance the leg 62 separating bias. It has been found, forexample, that a separation D-3 of approximately one-third of the depthof the groove 52 is adequate. This distance D-1 and the angle A-1between the two walls of the leg 62 is exaggerated in the illustrationof FIG. 5 which approximates the spacing prior to installation. Oncesnapped into place, as shown in FIG. 5, this distance may be aboutone-half the distance illustrated.

In a typical embodiment, the distance D-3 is about 1/8 inch once thecover plate has been snapped into place. The use of a radius of 1/16inch or less at the lower end of the legs insures a V-shaped leg whichincreases the resistance to lateral compression and hence the snap-lockof the coverplate into the groove. The spacing between the walls of thelegs is also reduced and provides adequate structural strength withoutthe presence of concrete therebetween. The tight radius at the lateraledge of the cover plate increases the amount of concrete in the groovewith the cover plate in place increases edge rigidity, thus increasingthe locking action.

As shown in FIG. 5, the laterally outward side of the dual wall legs 62is joined to the flat portion 56 of the outer section by an upwardly andoutwardly inclined portion 68. As shown in FIG. 6, each of the coverplates 50 may be provided with a first pair of laterally separatedknock-outs 70 encompassing laterally the entire space of the inclinedportion 68 and about seventy-five percent of the flat portion 56 of eachouter section. The effect of the reduction in the height of the flatportion 60 of the inner section below that of the flat portion 56 of theouter section (D-1 less D-4) provides an effective angle of entry A-2 tothe horizontal of about fifteen degrees. This effective downward andoutward entry into the outer two of the three longitudinal cells of theelectrified valley facilitates the handling of the electrical wiringcontained therein In addition, the reduction in height provides adequatespace for a duplex receptacle to be mounted in a generally verticalposition, thereby increasing the central working area of the presetinsert.

The height differential between the center and side cells is generally3/8 inch or more. In a nominally 3 inch deep deck, it may beapproximately 3/4 inch. This differential may of course be achieved byany differential in the relative height, i.e., the side cells may notrise to the level of the crests and the center cell may be either aboveor below the level at which the cover plate engages the sidewalls of thedecking members.

As shown in FIG. 6, each of the cover plates 50 may also be providedwith a second pair of longitudinally spaced knockouts 72 to provide twoentries into the flat portion 60 of the central cell of the electrifiedvalley.

As shown in FIG. 6, each of the cover plates may be provided with one ormore apertures 74 for the electrical grounding and mechanical attachmentby a screw to the metal decking members as described hereinafter ingreater detail in connection with FIGS. 7 and 8.

As also shown in FIG. 6, each of the cover plates may be provided withan aperture 76 and a laterally extending slot 78 located respectivelylaterally outside of the second pair of knock-outs 72. As is explainedin greater detail in connection with the preset insert of FIGS. 11, 12and 14, the aperture 76 and the slot 78 may be used to facilitate therapid attachment of the preset insert 80 to the cover plate 50 as shown,for example, in FIG. 4.

As illustrated in FIG. 4, the cover plates 50 of the present inventionare disposed in an end to end relationship overlying only the valleysintended to be electrified. These cover plates 50 may be of differentlengths, desirably multiples of the preset insert spacing, e.g., ten tofifteen feet, and may include one grouping of knock-outs as illustratedin FIGS. 4 and 6, or more as a function of length and the need foraccess to the electrical wiring contained therein. Access to thiselectrical wiring is achieved through a plurality of preset inserts eachmounted on the cover plates 50 in position to enclose one of thegroupings of knock-outs.

A second embodiment of the cover plate of the present invention is shownin FIG. 30 where the cell area is divided into two rather than threecells. Where the decking section of FIGS. 1 and 5 is used in the valleyarea, the lower end 64 of the dual wall legs 62 may rest in the groove48 in the stiffening bead 46. Lateral stability may also be enhanced bypositioning the leg 62 at one side of the bead 46 as shown in dashedlines. In either event, a significant difference in the relativecapacity may be achieved to accommodate the relatively small capacityrequirement of the power service and the relatively large potentialcapacity requirement of communications cables.

A third cover plate embodiment is shown in FIG. 31 where three cells areprovided in one valley, with access to the side cells facilitated by theheight differential of the center section 63 and the side sections 65 asin the cover plate of FIG. 5.

This height differential is also useful in the cover plate 234illustrated in FIGS. 32 and 34B. With reference to FIG. 32, the coverplate may be connected to the inclined side walls or web of the deck inthe snap-lock fashion described earlier and may rise to the height ofthe crests 220 thereof for the side section 236. The lateral extremitiesof the reduced height center section 238 form depending legs which maybe configured to mate with the tops of the ridges 232 of the deckingmember so as to provide isolation of the three cells and enhancedstability.

A fourth cover plate embodiment is illustrated in FIG. 36. Withreference again to FIG. 36, the cover plate 274 uses less steel incooperating with the decking member to form the longitudinal cells, thethree flat sections being separated by upwardly convex longitudinalgrooves 275, the lateral extremities of which form the depending legs ofthe cover plate. The cover plate may be secured in the grooves 264 inthe sidewalls 272 of the decking members in the manner earlier describedand/or attached directly to the cell dividers 260 of the decking memberby suitable metal fasteners 276 thus providing a secure mechanicalmounting and electrical ground.

The height differential between the center and side cells isapproximately 0.5 to 0.625 inches for a three inch deck and provides foran angled access to the lateral cells through knockouts 280. Access tothe central cell may be provided through knockouts 282, the knockouts280,282 being removed at the time the preset insert is activated.

A fifth cover plate embodiment is illustrated in FIGS. 39 and 40. Withreference to the figures, the cover plate 310 conforms generally to theconfiguration illustrated in FIG. 36 and is provided with a pair oflongitudinally spaced knock-outs 312 for the central power cell, and apair of laterally spaced knockouts 314 for the lateral cells. Theknock-outs 312 may be generally sem-circular, preferably semi-elipticalas shown, and the knock-outs 314 may be generally rectangular,preferably with rounded corners as shown. In conformity with thefootprint 316 of the preset insert hereinafter described in connectionwith FIG. 37, the cover plate may be provided with a slot 318 and a pairof apertures 320 by which the preset insert may be held securely inplace.

One of the grommets 322 illustrated in dashed lines in FIG. 39 isillustrated in greater detail in FIGS. 41 and 42. With reference to FIG.41 and 42, the grommet 322 is generally c-shaped in cross-section andmay be continuous. However, and as shown in FIGS. 39 and 40, the grommet324 for the apertures to be side cells need not be continuous and mayterminate at the junction of the outer surface 310 and the groove, asthe curved surface of the ribs or cell dividers 260 of the deckingmember provide a smooth exit for the wires 326 illustrated in FIG. 40.

Insert Pattern

The pattern of preset inserts generally desired is one of offset rowsand it is thus useful to position the inserts relative to the trenchheader. This may be accomplished in the present invention by thealternative use of short sections of cover plate of different lengths.

As illustrated in FIG. 46, the trench bottom plates 342 are positionedover beam opening lengths of deck 340 in the location of the trench.Trench rails 344 may then be positioned transverse of the deckingmembers 340, and covered by the trench cover 346.

For a total electrification system, by alternating a short section,e.g., one foot of cover plate 348 with a short section, e.g., 2.25 feet,and by locating the preset insert at the far end of the longer section,standard lengths, e.g., 15 feet, of cover plate 350 may be used toestablish the desired pattern.

As shown in FIG. 47, where electrified deck 352 is blended withnon-electrified deck 354, short sections without a preset insert (e.g.,two feet) are alternated with short sections (e.g., 4.5 feet) with aninsert adjacent one end to establish the pattern of offset rows.

Adaptation For Bar Joist Construction

The present invention is readily adapted for electrification of formdecks, i.e., decks generally supported by bar joists in which theconcrete slab is the primary structural element and the principalfunction of the metal deck is to provide a form over which the concreteslab is poured.

As shown in FIG. 48, the decking member 360 suspended between a selectedpair of bar joists 362 may take the form of the decking memberillustrated in FIG. 36, modified to eliminate the laterally outerportion of both crests 262 and the side lap valley 270. As illustratedin FIG. 48, the cover plate 364 may take the form of that illustrated inFIG. 36 and the preset insert 366 may be that illustrated in FIG. 37.

In a preferred embodiment, the header may take the form of a trench withside rails 368 and a trench cover plate 370. A longitudinal powerchannel may be provided as earlier described. Since the depth of thetrench is the full depth of the slab 380, and may be of any desiredwidth, the trench has adequate capacity.

The capacity of the distribution ducts formed by the decking member 360and cover plate 364 is also adequate for three services inasmuch as thedepth thereof is not limited by the depth of the concrete slab 380 andmay extend downwardly to the full depth of the bar joist if desired.

The location of the preset insert 366 directly on the cover plate 364rather than the form deck 382 permits the insert to occupy the entiredepth of the slab and thus greatly increases the capacity thereof. Thisrelationship allows the use of a submerged floor fitting in a relativelythin slab and is illustrated in FIG. 49. As shown in FIG. 49 the formdeck 382 need not overlie the area of the cover plates 364 as shown inFIG. 48 because the cover plates serve as the form to support theconcrete. If the form deck overlies the cover plates, it must beapertured for the preset insert.

ADVANTAGES AND SCOPE OF THE INVENTION

The many advantages of the present invention should be readily apparentto one skilled in the art to which this invention pertains. By way ofexample, the novel decking profiles provide increased strength andstacking stability over known prior art profiles. The grooveconstruction facilitates concrete holddown, the snap-in of cover plates,the snap-in of preset inserts, and the snap-in of bottom plates for thelateral trench. The elimination of apertures in the decking memberspermits the economical use of reduced strength reducing gauge steel.

The cover plates are self-supporting intermediate adjacent crests andprovide for unequal power and communication cells, as well as for threeservices, all in a single valley. By the use of a configuration withnarrow legs, there is no significant reduction in cell capacity. Thecell capacity is also increased by raising the height of the cover platein selected areas intermediate the crests. The one-piece constructionprovides ease of manufacture and the resiliency necessary for propersnap-lock retention.

The novel decking profiles provide adequate metal/concrete interaction,even with cover plates and preset inserts retained therein. Studs may beprovided in the side-lap valleys.

In combination with the profile of the cover plates, sufficient space isprovided for three services, with cell division provided by theresilient double walled legs and/or ridges in the decking member,particularly where the width of the central valley is greater than thatof the side-lap valleys.

Access to the cells beneath the cover plates is easily obtained throughsnap-in preset inserts with snap-in electrical receptacles. In someembodiments, the preset inserts are simultaneously attached to the coverplate and decking member by threaded fasteners to provide both a securemechanical mounting and electrical grounding.

The use of trench rails of sheet metal significantly reduces the expenseof the trench system, and the use of trench bottom plates eliminates theneed to interrupt the concrete in nonelectrified valleys by verticalconcrete stops, thereby improving the strength of the composite floor.The trench bottom plates may also serve to locate the trench side railsand the power cell.

The unique cooperation of the various elements of the system of thepresent invention significantly reduces labor costs. Moreover, many ofthe components are nestable and thus reduce the space required forshipment and the space required for on-site storage. In addition, thepossibility of damage during shipment is significantly reduced.

The various elements of the present system are easily adapted for barjoist construction and provide significantly increased capacity for athinner slab.

These and many more advantages will be readily apparent to one skilledin the relevant art. The invention is defined in the appended claims,the scope of which is therefore to include, without limitation, theexemplary embodiments disclosed in the foregoing specification whengiven a wide range of equivalents.

What is claimed is:
 1. A metal decking member having alternativelysubstantially coplanar crests and substantially coplanar valleysconnected by grooved sidewalls and a metal snapin cover plate to form athree-cell electrical raceway, said cover plate comprising:a singleelongated sheet of metal with three lateral sections, the outer two ofthree said sections having a flat portion at a first elevation and anouter edge portion being adapted to engage a groove in the sidewall ofthe decking member adjacent one of the crests, the inner one of saidthree sections having a flat portion lower than the flat portion of saidouter sections by 3/8 inch or more, the flat portion of said innersection being interconnected at its lateral extremities with the flatportions of said outer sections by a dual wall, longitudinally extendingleg open at the upper end and closed at the lower end, said closed endbeing adapted to engage the underlying decking member and thereby formwith the underlying decking member three longitudinally extending cellsfor electrical wiring, said legs being resiliently compressible in alateral direction adjacent said flat portions sufficiently to permit asnap-on engagement of said outer edge portions with the grooves in thesidewalls of the adjacent decking members.
 2. A metal decking memberhaving alternatively substantially coplanar crests and substantiallycoplanar valleys connected by sidewalls and a one piece metal coverpaate to form a three-cell electrical raceway within a single valley,said cover plate comprising:a single elongated sheet of metal with threelateral sections, the outer two of three said sections having a flatportion at the same elevation and an outer edge portion at an elevationlower than that of said flat portion, said outer edge portion beingadapted to engage a sidewall of the decking adjacent one of the creststo secure said cover plate to the decking member; the inner one of saidthree sections having a flat portion interconnected with the flatportions of said outer sections by a dual wall, longitudinally extendingleg open at the upper end and closed at the lower end, said closed endbeing adapted to engage the underlying decking member and thereby formwith the underlying decking member three longitudinally extending cellsfor electrical wiring in a single valley.
 3. A metal decking memberhaving alternatively substantially coplanar crests and substantiallycoplanar valleys connected by sidewalls and a metal cover plate to forma plural cell electrical raceway, said cover plate comprising outer edgeportions adapted to engage a sidewall of the decking member adjacent oneof the crests to thereby secure said cover plate to the decking memberat a height below the height of the crests of the decking member, and atleast one longitudinally extending leg adapted to engage a valley of theunderlying decking member and thereby form with the underlying deckingmember when secured thereto at least two longitudinally extending cellsfor electrical wiring,the upper surface of said cover plate rising abovethe height of said outer edge portions at one or more pointsintermediate said outer edge portions but spaced therefrom as to permitthe access of concrete poured thereover to the sidewalls of the deckingmembers above the elevations of said outer edge portions when said coverplate is secured to the decking member whereby the capacity of the cellsbeneath said cover plate is increased without loss of composite actionadjacent the crests of the decking member when said cover plate issecured thereto and concrete poured thereover.
 4. In combination with ametal decking member having alternatively substantially coplanar crestsand substantially coplanar valleys connected by sidewalls, saidsidewalls having a groove adjacent the crests, a one-piece metal snap-incover plate for forming a plural cell electrical raceway, said coverplate comprising:a single elongated sheet of metal with at least twolateral sections, said sheet having outer edge portions curved tosubstantially conform to the shape of the grooves in said sidewall tofacilitate the insertion therein and thereby position said cover plateover a valley of the decking member to form a longitudinally extendingelectrical raceway, said cover plate having a width greater than thespacing between adjacent crests and approximately the spacing betweengrooves, adjacent ones of said sections being interconnected by a dualwall, longitudinally extending leg, open at the upper end and closed atthe lower end, said closed end being adapted to engage the underlyingdecking member and thereby form with the underlying decking memberlongitudinally plural extending cells for electrical wiring, said legsbeing generally V-shaped with a radius of curvature of the lower endthereof not greater than 1/8 inch and resiliently compressible in alateral direction adjacent said sections sufficiently to permit asnap-in engagement of said outer edge positions with the grooves in thesidewalls of the decking member.
 5. The cover plate of claim 4 whereinthe number of said legs is two and the number of said lateral sectionsis three.
 6. The cover plate of claim 4 wherein the number of said legsis one and the number of said lateral sections is two, said one legbeing laterally displaced from the center of said cover plate to therebyform two cells or significantly different capacity.
 7. The cover plateof claim 6 wherein the valley of the decking member for which used alsoincludes at least one raised portion and wherein said leg engages theraised portion of the decking member when in position over the valley tothereby form said cells.
 8. The cover plate of claim 6 wherein thevalley of the decking member for which used also includes at least oneraised portion and wherein said leg engages the decking member adjacentthe raised portion when in position over the valley to thereby form saidcells.
 9. The cover plate of claim 6 wherein the capacity of said twocells has a ratio of about 2.5:1.
 10. In combination with a deckingmember having alternatively substantially coplanar crests andsubstantially coplanar valleys connected by sidewalls, a one-piece coverplate comprising:a single elongated sheet of metal with two lateralsections each having an outer edge portion adapted to engage a sidewallof the decking member adjacent one of the crests, and beinginterconnected by a dual wall, longitudinally extending leg open at theupper end and closed at the lower end, said closed end being adapted toengage the underlying decking member and thereby form with theunderlying decking member two longitudinally extending cells forelectrical wiring, said dual walls being sufficiently close together atsaid upper end to prevent any substantial amount of concrete fromentering the space there between.
 11. A metal decking member having twosubstantially coplanar crests and an interior valley connected bysloping sidewalls and a one-piece metal cover plate to thereby form anelectrical raceway, said cover plate comprising:a single elongated sheetof metal with three lateral sections; the outer two of three saidsections having flat portion at a first elevation and an outer edgeportion at an elevation lower than that of said flat portion, said outeredge portion being adapted to engage a sidewall of the decking memberadjacent one of the crests to thereby position said cover plate oversaid interior valley and contiguous sidewalls; the inner one of saidthree sections having a flat portion at a height below the height of theflat portions of said outer sections and interconnected therewith bydepending legs.
 12. The cover plate of claim 11 including means adjacentthe lateral extremities of said inner section adapted for engagementwith an upwradly extending ridge in the decking member.
 13. The coverplate of claim 12 wherein said inner section is below the height of saidouter edge portions whereby said cover plate may be positioned with saidouter edge portions engaging the side walls of a decking member, withsaid outer sections substantially coplanar with the crests thereof andwith said inner section below the height of the connection of said coverplate to the sidewalls of the decking member.
 14. The cover plate ofclaim 13 wherein the width ratio of inner to outer flat portions isabout 1:1.
 15. The cover plate of claim 13 wherein the width ratio ofinner to outer sectons is about 1.65:1.
 16. The cover plate of claim 11wherein the differnece in the height of the flat portion of said innersection and the flat portion of said outer sections is not less thanaobut 3/8 inch.
 17. The cover plate of claim 11 wherein the differencein elevation between the flat and outer edge portions of said outersections is such that said flat portions are substantially coplanar withthe crests of the metal decking member when used therewith and theelevation of the flat portion of said inner section is about theelevation of said outer edge portion.
 18. The cover plate of claim 11including a first pair of knockouts, each laterally spanning most of thewidth of one of said legs and more than about seventy-five percent ofthe width of one of the flat portions in said outer sections to therebyprovide, when removed, a downwardly and outwardly entrance through thecover plate to the area beneath said outer two longitudinal sections.19. The cover plate of claim 18 including a second pair of knock-outs insaid inner section, said second pair being longitudinally spaced frombut adjacent to said first pair to thereby provide two entrances to thearea beneath the inner longitudinal secton.
 20. The cover plate of claim19 including apertures in the flat portion of said inner section,longitudinally spaced one each outside of said second pair of knock-outsfor the attachment of a preset insert.
 21. In combination with a metaldecking member having two substantially coplanar crests and an interiorvalley connected by sloping sidewalls, a one-piece metal cover platecomprising:a single elongated sheet of metal with three lateralsections; the outer two of three said sections having a flat portion ata first elevation and an outer edge portion at an elevation lower thanthat of said flat portion, said outer edge portion being adapted toengage a sidewall of the decking adjacent one of the crests to therebyposition said cover plate over said interior valley and contiguoussidewalls; said three sections being separated by longitudinallyextending upwardly convex grooves.
 22. The cover plate of claim 21including a pair of knockouts each extending into one of said flatportions and the one of said grooves adjacent thereto.
 23. The coverplate of claim 22 wherein each of said knockouts are generally convexinto said flat portions.
 24. In combination with a metal decking memberhaving two substantially coplanar crests and an interior valleyconnected by sloping sidewalls, a one-piece metal cover platecomprising:a single elongated sheet of metal with three lateralsections; the outer two of three said sections having a flat portion ata first elevation and an outer edge portion at an elevation lower thanthat of said flat portion, said outer portion being adapted to engage asidewall of the decking adjacent one of the crests to thereby positionsaid cover plate over said interior valley and contiguous sidewalls; apair of longitudinally spaced, raceway access apertures in said innersection; and a pair of laterally spaced, raceway access aperturesextending one each into one of said outer sections longtidinallyintermediate said pair of longitudinally spaced apertures.
 25. The coverplate of claim 24 wherein said laterally spaced apertures are generallyarcuate and convex into said flat portions; andincluding a grommet forthe arcuate portion of said laterally spaced apertures.
 26. The coverplate of claim 24 wherein each of said longitudinally spaced aperturesis generally rectangular with a neck portion extending longitudinallytoward the other of said Iongitudinally spaced apertures; andincluding agrommet for each of said longitudinally spaced apertures, said grommetfollowing the rectangular shape of said aperture in the area of saidneck.
 27. In combination with a metal decking having alternativelysubstantially coplanar crests and substantailly coplanar valleysconnected by sidewalls, a one-piece metal snap-in cover plate for usewith said decking member to form a three-cell electrical raceway, saidcover plate comprising:a single elongate sheet of metal with threelateral sections, the outer two of three said sections having a flatportion at a first elevation and an outer edge portion at an elevationlower than that of said flat portion, said outer edge portion beingadapted to engage a sidewall of the decking adjacent one of the creststo thereby position said flat portions substantially coplanar with thecrests, the inner one of said three sections having a flat portioninterconnected with the flat portions of said outer sections by a dualwall, longitudinally extending leg open at the upper end and closed atthe lower end, said closed end being adapted to engage the valley of theunderlying decking and thereby form with the underlying decking threelongitudinally extending cells for electrical wiring, said legs beingresiliently compressible in a lateral direction adjacent said flatportions sufficiently to permit a snap-in engagement of said outer edgeportions with the sidewall of the decking member.
 28. The cover plate ofclaim 27 wherein the elevation of the flat portion of said inner sectionis less than the flat portion of said two outer sections,wherein saidlegs are joined to the flat portions of said outer portions by a sectionincluding an upwardly and outwardly inclined portion, and including afirst pair of knock-outs, each laterally spanning the width of one ofsaid inclined portions and more than about seventy-five percent of thewidth of one of said flat portions to thereby provide when removed adownwardly and outwardly entrance through the cover plate to the outertwo longitudinal cells.
 29. The cover plate of claim 28 including asecond pair of knock-outs longitudinally spaced in said inner section,each longitudinally spaced from but adjacent to the knock-outs in saidouter sections to thereby provide two entrances to the innerlongitudinal cell.
 30. The cover plate of claim 29 including a pair ofapertures in the flat portion of said inner section, said aperturesbeing longitudinally spaced one each outside of said second pair ofknock-outs for the attachement of preset insert.
 31. The cover plate ofclaim 27 wherein said outer edge portions include a generally flatportion and an upwardly curved portion presenting an outwardly convexsurface adapted to engage a groove in the upper sidewall of the deckingmember, said flat portion including a downwardly projecting longitudinalgroove apertured on the outer sidewall thereof to present a downwardlyand outwardly extending channel for a fastener through said lateral edgeinto the decking member.
 32. The cover plate of claim 31 wherein theelevation of the flat portion of inner section is less than the flatprotions of said outer sections,wherein said legs are joined to the flatportions of said outer portions by a section including an upwardly andoutwardly inclined portion, and including a first pair of knock-outs,each laterally spanning the width of one of said inclined portions andmore than about seventy-five percent of the width of one of said flatportions; and including a second pair of knock-outs in said innersection, the longitudinal spacing of said second pair being greater thanthe length of said first pair, said first pair being interior of saidsecond pair.
 33. The cover plate of claim 27 including means projectingfrom one wall of each of said dual wall legs toward the other wallthereof in the middle third of the length thereof to thereby increasethe resistance to compression of the upper ends thereof.